If you buy the El Gato EyeTV Hybrid USB stick tuner, I believe it advertises "zero-latency" for video game system inputs. You need to have a CPU capable of handling the encoding though, as there is no hardware encoding done inside the EyeTV. The stick runs $150 on Apple.com/store, and comes packaged with a "breakout" cable that allows for multiple inputs for recording from a DVD player/whatever, and allows use of the Mac's screen for a video game console.

Look go to newegg.com now and buy a EyEtv Hyrbid now. http://www.newegg.com/Product/Produc...82E16815131003
It costs $129.99 USD. Great device i play my xbox on it and there is absolutely no lag at all. The recording is great and you can even remote schedule through TITAN TV. Lets say you are off and cant get home to catch the soccer game. Get access to the internet and remotely schedule the program you want to watch then Eyetv will wake up your computer and record it.